Integrating Dual-Interfacial Liquid Metal Based Nanodroplet Architectures and Micro-Nanostructured Engineering for High Efficiency Solar Energy Harvesting

Abstract

Broadband strong absorption of solar light over a wide range of angles, low heat loss, and excellent structural reliability are of significance for enhancing solar harvesting of photothermal materials; however, it remains a challenge to achieve these attributes simultaneously. Herein, a tailored photothermal composite nanodroplet (LMP-rGO) featured with dual-interface, which comprises liquid metal (LM) core with polydopamine (PDA) photothermal middle layer of tunable thickness and reduced graphene oxide (rGO) shell, is particularly prepared. Thermal-insulating PDA coating and light-absorbing carbonaceous shell allow it to synergistically suppress heat loss and reinforce photon absorptivity. To maximize photothermal conversion and photon harvesting yield on solar light, inspired by light trapping architecture, a three-dimensional (3D) stepped micropyramid grating array framework is tactfully designed to ameliorate light coupling. Utilizing the scalability and cost-effectiveness of the poly­(vinyl alcohol) (PVA), the flexible 3D-structured PVA/LMP-rGO absorbers are successfully constructed via a controllable casting molding strategy. As a proof-of-concept, the developed micrograting absorber exhibits a desirable combination of strong broadband selective light absorption (94.9% for parallel to the grating direction and 97.3% for perpendicular to the grating direction), superior photothermal conversion effect (89.4%), high heat flux density, and fascinating mechanical properties. Also, an efficient and steady solar-driven thermoelectric generator (STEG) system for real-time solar-heat-electric conversion, with its high peak power density of 245.9 μW cm–2 under one sun irradiation, is further displayed, making an important step to rationally design LM-based nanocomposite droplets for solar energy harvesting.

Nanoarchitectonics and Applications of Gallium‐Based Liquid Metal Micro‐ and Nanoparticles

“…The micro-optical grating absorber made of this GLM nano-drop shows strong broadband selective light absorption (94.9% parallel to the grating direction, 97.3% perpendicular to the grating direction), excellent photothermal conversion effect, and high heat flux density. [43] GLM has high heat flux density and high thermal conductivity efficiency, which has great potential in the collection and utilization of solar energy. In general, the photothermal response of GLM particles means that they have important applications in many fields and can be used to improve human life.…”

“…The composition of the nanoparticles is GLM as the core of the particles, with adjustable thickness of polydopamine as the intermediate layer of the particles, and reduced fossil graphene as the shell of the particles. The micro‐optical grating absorber made of this GLM nano‐drop shows strong broadband selective light absorption (94.9% parallel to the grating direction, 97.3% perpendicular to the grating direction), excellent photothermal conversion effect, and high heat flux density [43] . GLM has high heat flux density and high thermal conductivity efficiency, which has great potential in the collection and utilization of solar energy.…”

Direct Writing of Liquid Metal onto an Electrospun Graphene Oxide Composite Polymer Nanofiber Membrane for Robust and Stretchable Electrodes

“…TPU was chosen as the elastic substrate for its high stretchability. [49] To address the problem of incompatibility between GaInSn and polymer substrate, [50,[56][57] GO, with abundant oxygencontaining groups, was introduced to improve the adhesion. The prototype electrode was constructed in three steps.…”

Microfluidic Methods for Generation of Submicron Droplets: A Review

“…In a photo-thermal-electric material for solar energy storage, liquid metal (LM) submicron droplets are coated with dual layers including a photo-adsorbing layer and a photo-thermal conversion layer. The LM nanodroplet in the core contributes to heat conduction [ 11 ]. In light upconversion materials, which are able to absorb low-energy light and emit high energy light, the submicron droplets are used as containers of the upconversion dyes [ 118 ].…”

“…This allows for submicron droplets that are widely presented in fields such as food [ 7 ], cosmetics [ 8 ], drug delivery [ 9 ], and composite materials [ 10 ]. Recently, in photo harvesting materials, liquid metal (LM) submicron droplets as the thermal conduction elements in a composite material, contribute to solar-heat-electric conversion [ 11 ]. In therapeutics, drugs can be loaded into the shells of core-shell submicron droplets [ 12 , 13 ], where an increased surface area is beneficial for drug-loading efficiency.…”